ABSTRACT
<p><b>BACKGROUND</b>To evaluate the incidence of multiple primary malignancies combined with lung and other organs and their relationship.</p><p><b>METHODS</b>All patients who consecutively treated for lung cancer from December 1964 to December 1992, were retrospectively analyzed regarding the recurrence of a synchronous primary tumor elsewhere in the body.</p><p><b>RESULTS</b>Of total 1019 patients reviewed, 21 (2.1%) had associated carcinoma of other organs. In these 21 patients, the incidence of associated aerodigestive tract cancer was 71.4% (15/21) and that of other organs was 28.6% (6/21). Five patients had simultaneous cancer with the lung cancer and 16 had metachronous cancer.</p><p><b>CONCLUSIONS</b>Multiple primary tumors in patients with carcinoma of the lungs is not a rare phenomenon. Surveillance programs for detection of second primary tumors should focus on these patients.</p>